Can't list big directories with pureftpd

I installed pureftpd on a VPS (ovh). I can list a small directory (by small I mean a directory with just some files) but if I try to list a big one containing maybe thousands of files, including directories I have a "Failed to retrieve directory listing" error message from filezilla client when I click on the "ps" directory : Command: USER xxxxx Response: 331 User xxxxx OK. Password required Command: PASS ************ Response: 230 OK. Current directory is / Command: OPTS UTF8 ON Response: 200 OK, UTF-8 enabled Status: Connected Status: Retrieving directory listing... Command: CWD /ps Response: 250 OK. Current directory is /ps Command: TYPE I Response: 200 TYPE is now 8-bit binary Command: PASV Response: 227 Entering Passive Mode (,156,188) Command: MLSD Response: 150 Accepted data connection Response: 226-Options: -a -l Response: 226 33 matches total Error: Connection timed out Error: Failed to retrieve directory listing From the command line I just have a never ending wait : ftp> cd ps 250 OK. Current directory is /ps ftp> ls 200 PORT command successful 150 Connecting to port 38359 I added this rules to iptables since I read it could fix the problem on my server : root@vpsxxx:/var/www/html# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:ftp-data ctstate RELATED,ESTABLISHED /* Allow ftp connections on port 20 */ ACCEPT tcp -- anywhere anywhere tcp spts:1024:65535 dpts:1024:65535 ctstate ESTABLISHED /* Allow passive inbound connections */ Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:ftp-data ctstate ESTABLISHED /* Allow ftp connections on port 20 */ ACCEPT tcp -- anywhere anywhere tcp spts:1024:65535 dpts:1024:65535 ctstate RELATED,ESTABLISHED /* Allow passive inbound connections */ I Added a fix port range for passive mode in pureftpd : root@xxx:/var/www/html# cat /etc/pure-ftpd/conf/PassivePortRange 40110 40210 root@xxx:/var/www/html# These are the permissions on my ps directory I'm trying to list : drwxr-xr-x 25 root root 4096 May 9 08:29 ps This is the iptables on my client os (Debian 8) : -P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT It looks like everything I tried is useless and has no effect. I tried to analyse the traffic with wireshark and it looks like I get part of my directory listing in a FTP-DATA protocol packet but then something is going wrong but I don't know what... Just noticed I had the same problem with proftpd, I thought it would work better with pureftpd, but no :)